/*
 * Copyright 2010 dev7.jp
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0 
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package jp.dev7.android.database;

import java.util.ArrayList;

import android.database.AbstractCursor;
import android.database.CursorIndexOutOfBoundsException;

/**
 * blobでバイト配列を運ぶためだけに作ったCursor.
 * 
 * @author narazaki.daishi
 */
public class ProtoBufCursor extends AbstractCursor {

    private final String[] columnNames;
    private Object[] data;
    private int rowCount = 0;
    private final int columnCount;

    /**
     * Constructs a new cursor with the given initial capacity.
     * 
     * @param columnNames
     *            names of the columns, the ordering of which determines column
     *            ordering elsewhere in this cursor
     * @param initialCapacity
     *            in rows
     */
    private ProtoBufCursor(String[] columnNames, int initialCapacity) {
        this.columnNames = columnNames;
        this.columnCount = columnNames.length;

        if (initialCapacity < 1) {
            initialCapacity = 1;
        }

        this.data = new Object[columnCount * initialCapacity];
    }

    /**
     * Constructs a new cursor.
     * 
     * @param columnNames
     *            names of the columns, the ordering of which determines column
     *            ordering elsewhere in this cursor
     */
    private ProtoBufCursor(String[] columnNames) {
        this(columnNames, 16);
    }

    public ProtoBufCursor() {
        this(new String[] { "byteArray" });
    }

    /**
     * Gets value at the given column for the current row.
     */
    private Object get(int column) {
        if (column < 0 || column >= columnCount) {
            throw new CursorIndexOutOfBoundsException("Requested column: "
                + column
                + ", # of columns: "
                + columnCount);
        }
        if (mPos < 0) {
            throw new CursorIndexOutOfBoundsException("Before first row.");
        }
        if (mPos >= rowCount) {
            throw new CursorIndexOutOfBoundsException("After last row.");
        }
        return data[mPos * columnCount + column];
    }

    /**
     * Adds a new row to the end and returns a builder for that row. Not safe
     * for concurrent use.
     * 
     * @return builder which can be used to set the column values for the new
     *         row
     */
    public RowBuilder newRow() {
        rowCount++;
        int endIndex = rowCount * columnCount;
        ensureCapacity(endIndex);
        int start = endIndex - columnCount;
        return new RowBuilder(start, endIndex);
    }

    /**
     * Adds a new row to the end with the given column values. Not safe for
     * concurrent use.
     * 
     * @throws IllegalArgumentException
     *             if {@code columnValues.length !=
     *  columnNames.length}
     * @param columnValues
     *            in the same order as the the column names specified at cursor
     *            construction time
     */
    public void addRow(Object[] columnValues) {
        if (columnValues.length != columnCount) {
            throw new IllegalArgumentException("columnNames.length = "
                + columnCount
                + ", columnValues.length = "
                + columnValues.length);
        }

        int start = rowCount++ * columnCount;
        ensureCapacity(start + columnCount);
        System.arraycopy(columnValues, 0, data, start, columnCount);
    }

    /**
     * Adds a new row to the end with the given column values. Not safe for
     * concurrent use.
     * 
     * @throws IllegalArgumentException
     *             if {@code columnValues.size() !=
     *  columnNames.length}
     * @param columnValues
     *            in the same order as the the column names specified at cursor
     *            construction time
     */
    public void addRow(Iterable<?> columnValues) {
        int start = rowCount * columnCount;
        int end = start + columnCount;
        ensureCapacity(end);

        if (columnValues instanceof ArrayList<?>) {
            addRow((ArrayList<?>) columnValues, start);
            return;
        }

        int current = start;
        Object[] localData = data;
        for (Object columnValue : columnValues) {
            if (current == end) {
                // TODO: null out row?
                throw new IllegalArgumentException(
                    "columnValues.size() > columnNames.length");
            }
            localData[current++] = columnValue;
        }

        if (current != end) {
            // TODO: null out row?
            throw new IllegalArgumentException(
                "columnValues.size() < columnNames.length");
        }

        // Increase row count here in case we encounter an exception.
        rowCount++;
    }

    /** Optimization for {@link ArrayList}. */
    private void addRow(ArrayList<?> columnValues, int start) {
        int size = columnValues.size();
        if (size != columnCount) {
            throw new IllegalArgumentException("columnNames.length = "
                + columnCount
                + ", columnValues.size() = "
                + size);
        }

        rowCount++;
        Object[] localData = data;
        for (int i = 0; i < size; i++) {
            localData[start + i] = columnValues.get(i);
        }
    }

    /** Ensures that this cursor has enough capacity. */
    private void ensureCapacity(int size) {
        if (size > data.length) {
            Object[] oldData = this.data;
            int newSize = data.length * 2;
            if (newSize < size) {
                newSize = size;
            }
            this.data = new Object[newSize];
            System.arraycopy(oldData, 0, this.data, 0, oldData.length);
        }
    }

    /**
     * Builds a row, starting from the left-most column and adding one column
     * value at a time. Follows the same ordering as the column names specified
     * at cursor construction time.
     */
    public class RowBuilder {

        private int index;
        private final int endIndex;

        RowBuilder(int index, int endIndex) {
            this.index = index;
            this.endIndex = endIndex;
        }

        /**
         * Sets the next column value in this row.
         * 
         * @throws CursorIndexOutOfBoundsException
         *             if you try to add too many values
         * @return this builder to support chaining
         */
        public RowBuilder add(Object columnValue) {
            if (index == endIndex) {
                throw new CursorIndexOutOfBoundsException(
                    "No more columns left.");
            }

            data[index++] = columnValue;
            return this;
        }
    }

    // AbstractCursor implementation.

    @Override
    public int getCount() {
        return rowCount;
    }

    @Override
    public String[] getColumnNames() {
        return columnNames;
    }

    @Override
    public String getString(int column) {
        Object value = get(column);
        if (value == null)
            return null;
        return value.toString();
    }

    @Override
    public short getShort(int column) {
        Object value = get(column);
        if (value == null)
            return 0;
        if (value instanceof Number)
            return ((Number) value).shortValue();
        return Short.parseShort(value.toString());
    }

    @Override
    public int getInt(int column) {
        Object value = get(column);
        if (value == null)
            return 0;
        if (value instanceof Number)
            return ((Number) value).intValue();
        return Integer.parseInt(value.toString());
    }

    @Override
    public long getLong(int column) {
        Object value = get(column);
        if (value == null)
            return 0;
        if (value instanceof Number)
            return ((Number) value).longValue();
        return Long.parseLong(value.toString());
    }

    @Override
    public float getFloat(int column) {
        Object value = get(column);
        if (value == null)
            return 0.0f;
        if (value instanceof Number)
            return ((Number) value).floatValue();
        return Float.parseFloat(value.toString());
    }

    @Override
    public double getDouble(int column) {
        Object value = get(column);
        if (value == null)
            return 0.0d;
        if (value instanceof Number)
            return ((Number) value).doubleValue();
        return Double.parseDouble(value.toString());
    }

    @Override
    public boolean isNull(int column) {
        return get(column) == null;
    }

    public ProtoBufCursor add(byte[] byteArray) {
        addRow(new Object[] { byteArray });
        return this;
    }

    @Override
    public byte[] getBlob(int column) {
        Object value = get(column);
        if (value == null)
            return null;
        return (byte[]) value;
    }
}
